The present invention relates to a paper folding machine for cutting a continuously fed web of paper into sections and folding the sections at a relatively high rate and without transferring the paper web from one roll to another.
Paper folding and cutting machines have long been well known in the paper handling art. Generally, these machines have the capability of performing multiple operations on either a continuous web of paper or on multiple separate pieces of paper fed into such machines. For example, a typical paper folding machine may include multiple drums or rolls performing specific functions such as feed rolls, folding rolls, knife rolls, ironing rolls and packer rolls. Typically, a continuous sheet or web of paper is either pulled or fed through a preliminary forming step which may include folding the sheet lengthwise in half. The once-folded web of paper can then be fed through successive rolls within the machine which perform various folding, cutting and packing functions on the web of paper. However, all such machines currently available commercially are relatively slow.
Generally, paper folding machines also have the capability of delivering the folded pieces of paper in a suitably stacked configuration. In some instances, a paper folding and cutting machine may be used in conjunction with another paper handling machine or operation such as a printing press or an envelope stuffing machine.
One type of paper folding machine commonly used can be described as a buckle-type paper folding machine. An example of a buckle-type machine is illustrated in U.S. Pat. No. 4,834,699 to Martin entitled xe2x80x9cBuckle Chute Paper Folding Apparatus.xe2x80x9d In a buckle-type machine, a piece of paper is fed or pulled through two elongated adjacent rollers that direct the leading edge of the piece of paper into a tray or a chute that is of a finite length and which stops the leading edge of the paper at a predetermined distance from the rollers. Once the leading edge hits the end of the chute, the paper is confined as it is buckled by the first pair of rollers which are still advancing the sheet of paper. The buckled portion of the piece of paper is then caught between another pair of rollers positioned next to the first pair of rollers. The second pair of rollers pull the buckled portion through, thereby creating a folded piece of paper. The buckle-type paper folding machine requires the transferring of a piece of paper between multiple sets of rolls which can result in increased frequency of paper jams.
Another example of a paper folding machine is described in U.S. Pat. No. 4,490,132 to Ogura et al. entitled xe2x80x9cPaper Folding Machines For Use in Rotary Presses.xe2x80x9d Ogura discloses a paper folding machine having multiple rolls and other mechanisms for conveying the sheets of paper and for folding and stacking the sheets of paper. Machines such as the one described in Ogura et al. comprise several rolls that perform the cutting, gripping and folding functions separately. The cutting of the continuous web of paper into separate sections is accomplished before the paper enters the portion of the machine where it is folded. Also, Ogura et al. discloses that the piece of paper is transferred from a first roll to a second roll in order to accomplish the folding procedure.
The disadvantage of present paper folding machines is a limitation on the speed of processing the paper due to the multiple rolls and the transferring of the paper from roll to roll. Also, multiple parts create a higher likelihood of malfunctions and paper jams and require increased maintenance and calibration in order to perform properly.
Thus, there continues to be a need for a paper folding machine that minimizes the number of rolls that a piece of paper must be fed over or through and that will increase the speed of the folding and cutting process, which results in increased productivity. The present invention meets these desires.
A paper folding machine embodying the present invention performs cutting and folding procedures on a continuously fed web of paper efficiently and at a relatively high rate. The web of paper may be folded longitudinally as it fed into the machine. The machine can be configured to fold the paper either once or multiple times as desired. The step whereby a longitudinally pre-folded web that is cut and folded once within the machine is referred to as a xc2xc (quarter) fold. The step whereby the xc2xc-folded piece is folded once more within the machine is referred to as an xe2x85x9 (eighth) fold. Of course, it is not necessary for the web to be longitudinally pre-folded. For simplicity, the terms xe2x80x9cxc2xc foldxe2x80x9d and xe2x80x9cxe2x85x9 foldxe2x80x9d are used herein without regard to pre-folding. Also, the finished product, i.e., the folded sections of paper, can be delivered in separate stacks of selectable variable count by alternately engaging and disengaging pack-off stations, if the machine is so equipped.
The paper folding machine of the present invention comprises a relatively large-diameter rotating hollow drum which includes a peripheral ring defining a drum outer surface. The drum includes grippers spaced from one another on the drum outer surface that hold sections of the web on the drum while the cutting and folding operations take place. The grippers can include vacuum sources or mechanical portions to grip the web. A knife for severing the web while the web is situated on the drum outer surface and being held by the grippers is also included in the machine. Also, a folding station is provided at the periphery of the drum for folding the web while on the rotating drum. The folding station includes a folding roll.
In the preferred embodiment described herein, the grippers are spaced such that the web can be gripped by two of the grippers while the web is cut by the knife. The knife is actuated in synchronism with the rotating drum.
The folding roll is adjacent to and para-axial with the drum and includes a retainer for releasably holding a leading edge of the web to be folded back over a trailing portion of the web while the drum rotates and the gripped portion moves past the folding roll, thereby providing a fold in the web. The folding roll is driven in synchronism with the rotating drum but rotated in a direction opposite that of the rotating drum.
The retainer of the folding roll of the preferred embodiment can comprise a vacuum source within the folding roll for drawing air through a port, whereby a suction effect is created for releasably holding the leading edge of the web against the folding roll while the folding roll rotates and the gripped portion of the web moves past the folding roll. Alternatively, or in a subsequent folding station, a folding arm can be included in the folding roll to remove the gripped portion of the section of the web from the drum and to fold the leading edge back over the trailing portion of the section.
A tucker roll can be included in the folding station. The tucker roll includes a tongue that extends radially outwardly from the periphery of the tucker roll for urging a portion of the web toward one of the grippers.
In another embodiment, the peripheral ring can define at least one knife aperture communicating with the interior of the drum. The knife aperture is situated between two adjacent grippers. In this embodiment, the knife can comprise a rotating body within the interior of the drum having two opposing cutting edges, such as blades, which extend at least partially through the knife apertures.
The folding roll that cooperates with the knife to cut the web and that provides the xc2xc fold can include an anvil extending radially outwardly from the folding roll for cooperating with the rotating knife to cut the web via a shearing action whereby a portion of the rotating knife protrudes through an aperture of the drum and cooperates through the aperture with the anvil of the folding roll to sever the web.
An alternate embodiment of the paper folding machine of the present invention can include a subsequent folding station which also includes a folding roll and a tucker roll. The subsequent folding station can be provided to perform the xe2x85x9 fold operation. Additional folding stations can be provided to provide even more folds such a {fraction (1/16)} (sixteenth) fold (or more).
An ironing roll can be provided, if desired, to press against the folded section in order to flatten the fold by creating a crease.
Another optional feature can be a pack-off station for cooperating with the drum to remove the folded sections of the web. The pack-off station can also stack the folded product, and, if desired, can provide separate stacks of folded product.
There are other advantages and features of the present invention which will be more readily apparent from the following detailed description of the preferred embodiment of the invention, the drawings and the appended claims.